Liquids are often stored and sold in boxes or containers which facilitate a compact packing and easy handling of the liquid. By storing the fluid in a flexible bag within the box—a so-called bag-in-box—any amount of the liquid can be tapped from the container without air getting in contact with the liquid. This is advantageous for instance when tapping wine, as a consumer in this way is given the opportunity to enjoy a single glass of wine from the bag-in-box without the remainder of the wine in the container having to be used within a limited time in order to taste the best.
Usually the tap or dispenser on a bag-in-box is initially concealed within the box so that the boxes can be packed and stored as compactly as possible and so that the tap is not damaged during the handling of the boxes. When the liquid is to be dispensed the consumer has to break the cardboard box open along a perforation and find the tap structure with the fingers from within the box. The tap is then on most containers partly pulled out of the box and positioned in the cutout of the box and held somewhat in position by means of a flap from the cardboard box. However, after opening the box usually appears rather deteriorated and with a flawed look yielding an unfortunate impression of a cheap product. Also, the fastening of the tap in the opening of the box is most frequently very loose and shaky whereby the dispensing becomes more difficult, especially when the bag inside becomes only halfway full.
Different types of telescope taps for bag-in-boxes are known from the literature where the dispensing units are equipped with different types of valves for the tapping of the liquid. However, the telescope taps known in the art posses a number of different disadvantages such as taking up a considerably large amount of space within the box, not providing an easy mode of operation for the user, or consisting of a relatively large number of mechanical parts with complicated shapes thereby making the tap rather expensive to manufacture and inappropriate for a disposable product.
WO 81/00608 describes a telescope tap consisting in essence of a pipe which is to be heat sealed to the inner flexible bag in a bag-in-box. When employed, the user extracts the pipe from the box and operates the tap by deforming a membrane at the outer end of the pipe whereby a valve is opened. One large disadvantage of the construction of this telescope tap is, however, that the tap in its closed position takes up some space within the box whereby the inner bag must be squeezed somewhat together in order to still be able to fit into the box. Furthermore, when extracted, the pulling force applied to the tap is passed on to the bag which is also pulled towards the box wall resulting in an increased risk for leaks in the seal between the tap and the bag.
Another kind of telescope tap is described in EP 0350243. Here a telescope pipe can be extracted from within a house passage leading from the box wall to the bag opening. This design too, however, takes up quite some space within the box and thus the bag must be made in a special shape in order not to fold or wrinkle around the tap. Furthermore, the design comprises parts with more complicated shapes such as double pipes and annular cavities which inevitably make the manufacture more expensive. Also, the described tap is designed to fit into a hole in a cardboard box and being fixed to the box wall by pressing together two parts of the tap from each side of the wall. The bag is then filled through the tap as the final step, which, however, makes the filling process more complicated both with the risks of spilling on the box destroying its appearance and of wearing the assembly of the tap to the box.